An exoplanet approximately the size of Jupiter, located 280 light-years away from Earth, was recently analyzed by NASA’s James Webb Space Telescope (JWST).
The scientific instruments on board the equipment are so sensitive that they were able to measure the climate on that distant world, discovering that the average temperature there is extremely high.
First detected in 2011, the exoplanet in question is called WASP-43 b, a gas giant that orbits a K-type star in the constellation Sextans. Before Webb, it had already been observed by the Hubble and Spitzer space telescopes, also from NASA.
About the exoplanet WASP-43 b:
- Mass: 1.78 times that of Jupiter
- Radius: 0.93 times that of Jupiter
- Orbital period: 19.5 Earth hours
- Distance from host star: 2,092,000 km
Using the telescope’s mid-infrared light spectrometer, an international team of scientists managed to map the climate on that planet’s surface – and the results of the research were published in the journal Nature Astronomy last week.
What the exoplanet WASP-43 b looks like
Scientists suggest that WASP-43 b is covered by a thick layer of clouds on one side, clear skies on the other, and vicious equatorial winds that can accelerate up to eight thousand km per hour. Considering the distances involved, these discoveries are truly fascinating.
The distance between the exoplanet and its host star is just 2,092,000 km, equivalent to 4% of the distance between Mercury and the Sun, resulting in scorching surface temperatures. This added to the dimensions classifies WASP-43 b as a “hot Jupiter” type planet.
With such a tight orbit, it is tidally locked, with one side continually lit and the other always dark. Although the night side never receives direct radiation from the star, strong easterly winds transport heat from the day side.
According to Taylor Bell, a researcher at the Bay Area Environmental Research Institute (BAERI) and lead author of the study, that world is much hotter than any gas giant in the Solar System. “With Hubble, we could clearly see that there is water vapor on the day side, and both Hubble and Spitzer suggested that there may be clouds on the night side,” he said in a NASA statement. “But we needed more precise measurements from Webb to really start mapping temperature, cloud cover, winds and more detailed atmospheric composition across the planet.”
James Webb detects iron-melting temperature on the day side of the planet
By analyzing the mid-infrared light emitted by WASP-43 b, scientists were able to conclude its exact temperature: 1,250ºC on its day side, which is hot enough to melt iron, and 600ºC on its night side.
Webb’s Mid-Infrared Instrument (MIRI) was used to measure the light emitted by the WASP-43 system every 10 seconds for more than 24 hours. This analysis led to the construction of an approximate map of temperature across the planet. “By observing over an entire orbit, we were able to calculate the temperature of different sides of the planet as they came into view,” explained Bell.
These observations allowed the team to use complex 3D atmospheric models, similar to those used to study the climate on Earth, creating the climate map of the planet WASP-43 b.
Thanks to Webb, the study was also able to measure the amount of water vapor (H2O) and methane (CH4) around the planet.
The spectra reveal clear evidence of the presence of water vapor on both the night and day sides of the planet, offering additional information about the density and altitude of clouds in the atmosphere.
Surprisingly, the data also indicates a notable absence of methane throughout the atmosphere. Although the day side is too hot to support methane (with most of the carbon likely in the form of carbon monoxide), methane was expected to be stable and detectable on the cooler night side.
It was the absence of methane that made researchers conclude wind speeds of more than eight thousand km per hour. According to the study, if winds move gas from the day side to the night side and back quickly enough, there is no time for the expected chemical reactions to produce detectable amounts of methane on the night side.
The team thinks that because of this wind-driven mixing, atmospheric chemistry is the same across the planet, which was not apparent in previous work with Hubble and Spitzer.
